In the past few decades Voice over Internet Protocol (VoIP) is gaining a lot of attention due to the tremendous growth of the public internet leading the way into the IP world of communication. The performance degradation of the 802.11 (a/b/g) standards is mainly due to channel utilization, contention delays and collisions. The intension of this paper is described in two folds. The comparative study on call capacity of WLANs standards 802.11 (a/b/g/e) in terms of total delay, bandwidth utilization and throughput. This comparison is based on the same traffic circumstances and from the comparison; an effective standard which has a high call capacity in the VoIP over WLAN is estimated.